1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a superconducting magnet apparatus for generating a magnetic field by receiving an electric current from an external power source, and a control method thereof.
2. Description of the Related Art
With the development in a coil manufacturing technology using a superconducting magnet as well as the advance of relevant devices, such as an insulating container and a refrigerating device, a superconducting magnet apparatus and applications thereof have been developed. The superconducting magnet apparatus includes a superconducting magnet for a superconducting magnet apparatus or a superconducting magnet for a self levitation vehicle. The superconducting magnet apparatus becomes a persistent current state by receiving an electric current from an external power source through a coil that is cooled to a very low temperature. If the superconducting magnet apparatus has become a persistent current state, the output of the external power source is stopped and the superconducting magnet apparatus is driven in a state of being disconnected to the external power source.
The superconducting magnet apparatus requires a current lead when supplying coils with the electric current. The current lead represents a path connecting from a terminal connected to the external power source to a coil existing inside the superconducting magnet apparatus. The current lead is a thermal invasion path along from an ambient temperature terminal, which connects to the external power source, to a very low temperature coil. In a no current state, the current lead becomes an electric heating material. In order to minimize the refrigeration cost of a coil in a superconducting magnet for a superconducting magnet apparatus, the thermal invasion needs to be as small as possible. As a method of reducing the thermal invasion into the superconducting magnet, for a superconducting magnet apparatus operating in a persistent current mode, a demountable current lead is used such that the demountable current lead is separated when a current does not flow, thereby reducing the amount of thermal invasion. However, such a structure of connecting or disconnecting a current lead is handled only by a specialist, and also causes a great workload in a case that an electric current needs to be supplied as an occasion demands.